EP2178203A1 - Élément d'antenne actif pour communications radio mobiles - Google Patents

Élément d'antenne actif pour communications radio mobiles Download PDF

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Publication number
EP2178203A1
EP2178203A1 EP08017958A EP08017958A EP2178203A1 EP 2178203 A1 EP2178203 A1 EP 2178203A1 EP 08017958 A EP08017958 A EP 08017958A EP 08017958 A EP08017958 A EP 08017958A EP 2178203 A1 EP2178203 A1 EP 2178203A1
Authority
EP
European Patent Office
Prior art keywords
signal
antenna element
pulse
class
amplifier module
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08017958A
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German (de)
English (en)
Inventor
Andreas Dr. Pascht
Dirk Wiegner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Alcatel Lucent SAS
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Alcatel Lucent SAS
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Filing date
Publication date
Application filed by Alcatel Lucent SAS filed Critical Alcatel Lucent SAS
Priority to EP08017958A priority Critical patent/EP2178203A1/fr
Publication of EP2178203A1 publication Critical patent/EP2178203A1/fr
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
    • H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
    • H03F3/217—Class D power amplifiers; Switching amplifiers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/02—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/32—Modifications of amplifiers to reduce non-linear distortion
    • H03F1/3241—Modifications of amplifiers to reduce non-linear distortion using predistortion circuits
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/189—High-frequency amplifiers, e.g. radio frequency amplifiers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/68—Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics

Definitions

  • the invention relates to an active antenna element for mobile radio communications, comprising: an amplifier module for amplifying a RF signal and an antenna for transmitting the amplified RF signal.
  • the invention also relates to a transmit fronted for a base station comprising a plurality of such active antenna elements, to a radio network comprising at least one base station with such a transmit frontend, and to a method for amplifying a RF signal in an active antenna element.
  • the invention relates to applications in mobile radio communications, more particularly to the transmit path of base stations, in particular of base transceiver stations (BTS).
  • BTS base transceiver stations
  • the RF signal has to be amplified at some location in the transmit path, typically in the transmit frontend of the BTS,
  • this object is met by an active antenna element as described in the introduction, wherein the amplifier module is a class-S amplifier module comprising a transistor switching stage and a reconstruction filter.
  • the invention advantageously combines the active antenna approach with the promising class-S amplifier concept, i.e. the basic idea of the invention is to use highly efficient class-S based amplifiers in active antenna elements instead of e.g. class-AB amplifiers, Although it is known to use class-S amplifiers for audio applications, the use of class-S amplifiers for mobile radio applications, in particular in the context of active antenna elements, is a new and promising approach.
  • a pulse-width or delta-sigma modulated signal is amplified in the transistor switching stage, and a reconstruction filter (typically a band-pass or low-pass filter) serves to eliminate unwanted spectral components, e.g. the switching frequency and its harmonics, from the amplified RF signal.
  • a reconstruction filter typically a band-pass or low-pass filter
  • the RF signal to be amplified is typically a digital signal
  • a pulse-width or delta-sigma modulator may be arranged in the transmit path before the transistor switching stage.
  • the antenna element further comprises a feedback path from the output of the transistor switching stage to a pulse-width modulator or a delta-sigma modulator for self-linearization of the amplification.
  • Linearization of the amplification within the class-S amplification module may be required, which may be performed e.g. by an appropriate adjustment of the pulse-width modulator or delta-sigma modulator using the pulse-width or delta-sigma modulated signal at the output of the transistor as a feedback signal, resulting in a kind of pre-distortion of the pulse-width or delta-sigma modulated RF signal at the input to the transistor switching stage which compensates the distortion caused by the amplification in the transistor switching stage.
  • the antenna element further comprises a feedback path from the output of the reconstruction filter to a digital pre-distortion unit for linearization of the amplification by digital pre-distortion of the RF signal.
  • Digital pre-distortion may be used to correct for the distortion caused in the amplifier module by pre-distorting the (digital) RF signal before the pulse-width or delta-sigma modulation in a way which reverses the distortion caused by the amplifier, resulting in an amplified RF signal at the output to the amplifier module which shows no or only little distortion.
  • the (analog) reconstructed signal at the output of the reconstruction filter being no longer pulse-width or delta-sigma modulated, may be converted to a digital signal using an A/D-converter.
  • the class-S amplifier module comprises a pulse-width modulator or a delta-sigma modulator.
  • the pulse-width modulator may be implemented as a digital device, or as an analog device, e.g. as an application-specific integrated circuit (ASIC).
  • ASIC application-specific integrated circuit
  • the antenna element further comprises a D/A-converter and a mixer at an input to the pulse-width or delta-sigma modulator of the class-S amplifier module,
  • D/A-conversion and typically also mixing (frequency conversion) of the digital RF signal transmitted from the baseband part is required.
  • a transmit frontend for a base station comprising a plurality of active antenna elements as described above.
  • a base station comprises a transmit frontend with one or several antennas in an array arranged remotely from the baseband part.
  • power scalability and support of e.g. MIMO(multiple-input multiple-output)-schemes or spatial-forming can be achieved.
  • the transmit frontend comprises a baseband part connected to the plurality of antenna elements, the baseband part comprising at least one digital pulse-width modulator or delta-sigma modulator.
  • a modulator may be realized e.g. as a field programmable gate array (FPGA) in the baseband part, allowing to apply different delays to each class-S amplifier module in order to compensate e.g. for different delays of the active antenna elements.
  • FPGA field programmable gate array
  • a further aspect is implemented in a radio network comprising at least one base station with a transmit frontend as described above, the radio network advantageously using the high efficiency of the class-S amplifier modules of the antenna elements of the base station.
  • Yet another aspect is implemented in a method as described in the introduction, comprising: amplifying the RF signal in a transistor switching stage of a class-S amplifier module of the antenna element, thus increasing the efficiency of the amplification in the active antenna element.
  • a preferred variant includes: linearizing the amplification by using the amplified RF signal as a feedback signal.
  • the output signal from the transistor switching stage or from the reconstruction filter may be used as a feedback signal to compensate for distortions caused by the amplification.
  • the feedback signal is fed to a pulse-width modulator or to a delta-sigma modulator for self-linearization of the amplification.
  • a pulse-width modulator or to a delta-sigma modulator for self-linearization of the amplification.
  • the feedback signal is fed to a digital pre-distortion unit for digital pre-distortion of the RF signal in order to achieve a linear amplification of the RF signal.
  • a digital pre-distortion unit for digital pre-distortion of the RF signal in order to achieve a linear amplification of the RF signal.
  • Fig. 1 shows a transmit frontend 1 of a base station for mobile radio communications being part of a radio network 2.
  • the transmit frontend 1 may be implemented e.g. as a Node B when using the UMTS (universal mobile telecommunications) standard.
  • the transmit frontend 1 comprises a baseband part 3 which is connected via cabling to four active antenna elements 4a to 4d being of identical construction.
  • Each active antenna element 4a to 4d comprises a class-S amplifier module 5 for amplifying a respective RF signal 6a to 6d , and an antenna 7 for radio transmission of the respective amplified RF signal 6a' to 6d' .
  • the array of four parallel antenna elements 4a to 4d may, for example, be used for supporting a MIMO scheme and shows increased power scalability.
  • the amplification of the first RF signal 6a which is provided as a digital signal from the baseband part 3 to the input of the first active antenna element 4a will be described in greater detail.
  • the first RF signal 6a is converted to an analog signal in a D/A-converter 8 of the first active antenna element 4a and subsequently frequency conversion is performed in a mixer 9
  • the input signal of the mixer 9 is on baseband RF level in the MHz range, the output signal of the mixer 9 is the addressed transmit RF frequency which is then fed to the class-S amplifier module 5.
  • the class-S amplifier module 5 comprises an analog modulator 10 in the form of a pulse-width modulator, a transistor switching stage 11, and a reconstruction filter 12.
  • the modulator 10 may alternatively be implemented e.g. as an analog delta-sigma modulator.
  • the analog digital RF signal 6a is pulse-width or delta-sigma modulated in the modulator 10 and is then used to drive the transistor switching stage 11 at a switching frequency corresponding to the pulse frequency of the pulse-width or delta-sigma modulation.
  • the reconstruction filter 12 is then used to filter unwanted spectral components, in particular the pulse frequency and its harmonics, out of the amplified RF signal 6a' and to generate an (analog) output signal which corresponds essentially to the RF input signal 6a.
  • the person skilled in the art will appreciate that it is not necessary to devise the D/A-converter 8, the mixer 9 and the modulator 10 as separate components, as it is also possible to use an ASIC which integrates the functions of all three of these elements.
  • the output of the transistor switching stage 11 may be used to generate a kind of pre-distortion of the pulse-width or delta-sigma modulated signal, thus enabling a self-linearization of the class-S amplifier module 5.
  • a further feedback path 14 may be provided from the output of the reconstruction filter 12 to a digital pre-distortion unit 15 arranged in the baseband part 13 of the transmit frontend 1.
  • the digital pre-distortion unit 15 is used for generating a pre-distortion of the digital RF signal 6a in the opposite way as compared to the distortion caused by the class-S module 5, such that the pre-distorted RF signal 6a may be amplified in a linear way in the class-S amplification module 5.
  • the transmit frontend 1 of Fig. 1 comprises analog class-S amplifier modules 5
  • Fig. 2 shows an alternative way of implementing a transmit frontend 1 as a fully digital device up to the reconstruction filter 12.
  • the transmit frontend 1 of Fig. 2 has exemplarily three active antenna elements 4a' to 4c', each of which comprises a class-S amplifier module 5' with a transistor switching stage 11 and a reconstruction filter 12, all three antenna elements 4a' to 4c' sharing a common digital pulse-width or delta-sigma modulator block 10' arranged in the baseband part 3 of the base station 1, being implemented as a FPGA.
  • no D/A-converter is required, although also in this case, a mixer may be provided for frequency conversion, if e.g.
  • the FPGA modulator 10' does not meet the bandwidth requirements.
  • Using one modulator for all of the antenna elements 4a' to 4c' or more (synchronized) pulse-width or delta-sigma modulators in the modulator block 10' of the baseband part 3 allows to apply different delays to each Class-S amplifier module 5' in order to compensate e.g. different delays of the active antenna elements 4a' to 4c'.
  • feedback paths 13, 14 may be provided, leading from the output of the transistor switching stage 11 or from the output of the reconstruction filter 12 to the pulse-width or delta-sigma modulator 10' or to the digital pre-distortion module 15, respectively.
  • the pulse-width or delta-sigma modulator 10 of the Class-S amplifier module 5 may also be realized as a digital modulator which may be included in the active antenna elements 4a to 4d, being fed with a digital RF input signal 6a to 6c from the baseband part 3, thus also dispensing with the need for D/A-conversion.
  • class-S amplifier module(s) 5, 5' in the active antenna elements 4a to 4d, 4a' to 4c' allows increasing the efficiency of the power amplification and also the efficiency of the transmit frontend 1 e.g. by dropping the lossy cabling between power amplifier 5, 5' and antennas 7.
  • high power scalability can be achieved and MIMO or spatial beam forming applications may be supported.
  • the approach described herein is flexible and applicable to different frequency bands and communication standards.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Amplifiers (AREA)
EP08017958A 2008-10-14 2008-10-14 Élément d'antenne actif pour communications radio mobiles Withdrawn EP2178203A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP08017958A EP2178203A1 (fr) 2008-10-14 2008-10-14 Élément d'antenne actif pour communications radio mobiles

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP08017958A EP2178203A1 (fr) 2008-10-14 2008-10-14 Élément d'antenne actif pour communications radio mobiles

Publications (1)

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EP2178203A1 true EP2178203A1 (fr) 2010-04-21

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EP08017958A Withdrawn EP2178203A1 (fr) 2008-10-14 2008-10-14 Élément d'antenne actif pour communications radio mobiles

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2955845A1 (fr) * 2014-06-12 2015-12-16 Alcatel Lucent Architecture d'amplificateur de puissance à mode de commutation comprenant un filtre de reconstruction polyharmonique

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001008259A1 (fr) * 1999-07-22 2001-02-01 Fujant, Inc. Reseau actif a variation de phases reconfigurable
US6794931B2 (en) * 2000-02-25 2004-09-21 Andrew Corporation Switched amplifier
US6993087B2 (en) * 2001-06-29 2006-01-31 Nokia Mobile Phones Ltd. Switching mode power amplifier using PWM and PPM for bandpass signals
US20070160164A1 (en) * 2005-11-18 2007-07-12 Sahota Gurkanwal S Digital transmitters for wireless communication

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001008259A1 (fr) * 1999-07-22 2001-02-01 Fujant, Inc. Reseau actif a variation de phases reconfigurable
US6794931B2 (en) * 2000-02-25 2004-09-21 Andrew Corporation Switched amplifier
US6993087B2 (en) * 2001-06-29 2006-01-31 Nokia Mobile Phones Ltd. Switching mode power amplifier using PWM and PPM for bandpass signals
US20070160164A1 (en) * 2005-11-18 2007-07-12 Sahota Gurkanwal S Digital transmitters for wireless communication

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
FREDERICK H RAAB ET AL: "Power Amplifiers and Transmitters for RF and Microwave", IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, IEEE SERVICE CENTER, PISCATAWAY, NJ, US, vol. 50, no. 3, 1 March 2002 (2002-03-01), XP011038657, ISSN: 0018-9480 *
MONTES L A ET AL: "Specification of a polar sigma delta architecture for mobile multi-radio transmitter - validation on IEEE 802.16e", RADIO AND WIRELESS SYMPOSIUM, 2008 IEEE, IEEE, PISCATAWAY, NJ, USA, 22 January 2008 (2008-01-22), pages 159 - 162, XP031237123, ISBN: 978-1-4244-1462-8 *
RAAB F H ET AL: "L-BAND TRANSMITTER USING KAHN EER TECHNIQUE", IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, IEEE SERVICE CENTER, PISCATAWAY, NJ, US, vol. 46, no. 12, PART 02, 1 December 1998 (1998-12-01), pages 2220 - 2224, XP000805603, ISSN: 0018-9480 *
TSAI-PI HUNG ET AL: "Design of H-Bridge Class-D Power Amplifiers for Digital Pulse Modulation Transmitters", IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, IEEE SERVICE CENTER, PISCATAWAY, NJ, US, vol. 55, no. 12, 1 December 2007 (2007-12-01), pages 2845 - 2855, XP011197404, ISSN: 0018-9480 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2955845A1 (fr) * 2014-06-12 2015-12-16 Alcatel Lucent Architecture d'amplificateur de puissance à mode de commutation comprenant un filtre de reconstruction polyharmonique

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